This invention relates to a restraint device for an occupant in a vehicle having a steering wheel, a dashboard with a lower end limiting a footwell, an A-pillar and a windshield.
In certain accident situations, known vehicle occupant restraint devices comprising a gas bag for protecting the thorax area of a vehicle occupant often provide only an insufficient protection against injuries of the cervical spine.
By means of the invention a vehicle occupant restraint device is provided, which can flexibly adapt to the respective accident situation, and by means of which the risk of injury of a vehicle occupant can be kept extremely small. The restraint device according to the invention for an occupant in a vehicle having a steering wheel, a dashboard with a lower end limiting a footwell, an A-pillar and a windshield, comprises a first gas bag for protecting the thorax area of a vehicle occupant, and a second gas bag for supporting the first gas bag. The second gas bag has a deployed condition and extends at least partly over the windshield of the vehicle in the deployed condition.
If required in the case of a vehicle collision, the additional second gas bag serves as a support for the first gas bag and maintains the same in a predetermined position during the course of the accident, so that an optimum protective function of the first gas bag is ensured. The ensured defined position of the first gas bag and the perhaps possible division of the impact energy of the vehicle occupant over two separate gas bags allows to reduce the volume of the first gas bag from about 100 to 150 liters of commonly used thorax gas bags to about 70 to 90 liters without impairing the protective effect. Due to the reduction of the required gas quantity, less expensive gas generators can thus be used for inflating the gas bag. In addition, the use of a gas bag of reduced volume provides for a reduction of the inflation time as compared to conventional thorax gas bags, and the occupant has a reduced risk of injury during the process of deployment.
The second gas bag in addition prevents a contact of the head of the occupant with the windshield, where the arrangement of the two gas bags creates a specific freedom of movement for the head of the vehicle occupant, so that the acceleration moments acting on the neck are minimized during an accident. This provides for a significant reduction of the load acting on the cervical spine.
Preferably, the second gas bag is arranged such that in the deployed condition it is supported on the windshield. This ensures an optimum protective effect for the vehicle occupant, as with such a constellation the first gas bag is indirectly supported on the windshield via the second gas bag, and thus the impact of the vehicle occupant can optimally be absorbed. To furthermore avoid head injuries due to a possible contact of the head of the vehicle occupant with the A-pillar of the vehicle in the case of an inclined or offset impact, the second gas bag preferably extends over at least a portion of the A-pillar in the deployed condition.
From a functional and constructional point of view it has turned out particularly advantageous to accommodate the second gas bag in the roof liner of the vehicle. In this preferred embodiment, the second gas bag is deployed from the top to the bottom along the windshield, which involves no hazard potential for the occupant during the deployment of the gas bag, especially when the occupant is out of position, so to speak, has no normal seating position. This is often the case with children on the front seats. In particular in the case of convertible cars, which do not have a solid roof, the second gas bag can, however, also be accommodated in the dashboard or in the region of the A-pillar of the vehicle.
In the case of vehicles having both a driver-side and a passenger-side restraint means with one gas bag each for protecting the thorax area, the second gas bag advantageously extends substantially over the entire width of the windshield. In the case of a collision it can then serve as a support both for the driver-side and for the passenger-side thorax gas bag. However, there may also be provided two separate systems with one inventive vehicle occupant restraint device each.
In a further embodiment of the inventive device a traction system is provided, which after a vehicle collision pulls the deployed second gas bag away from the windshield, in order to again clear the field of vision for the driver and/or the passenger.
The first gas bag for protecting the thorax area of the vehicle occupant may be accommodated in the steering wheel in the case of a device for the driver of a motor vehicle, or in the dashboard of the vehicle in the case of a device for the passenger. An additional protective function is obtained in the latter case by accommodating the first gas bag in the lower portion of the dashboard limiting the footwell. The gas bag extending from the footwell over the dashboard in the deployed condition then also performs the function of a knee protection device.
An additional protection of the knee area of the vehicle occupant can also be achieved in that a third gas bag is provided, which is deployed in the footwell of the vehicle. A particularly space-saving embodiment is one where a gas generator is provided for inflating more than one of the gas bags.
An even better adaptation to the respective accident situation and also to the parameters of the vehicle occupant is obtained in that a multi-stage gas generator is used for inflating at least the first gas bag. Depending on the intensity of the vehicle collision and the weight of the vehicle occupant, the first gas bag can for instance be inflated harder or less hard. This also provides for a controlled time delay during inflation.